The HTC HD2 just refuses to die. The phone was released in November of 2009. Now, over five years later, the HD2 is getting updated to the most recent version of Android before the majority of current Android devices are seeing the update. Thanks to the prowess of developers over on XDA Forums, you can update your HD2 and start using Lollipop on this zombie smartphone. Seriously, this thing keeps coming back from the dead.
The ROM in question is in alpha stages at the moment, so proceed with caution. It boots, but that's almost all we have right now. The display works, as does the device audio. This is still very much a work in progress. The dev who got this working is macs18max, and he has committed to continue work on it until everything is working properly, not just the display and audio. The ROM is based on CM12, although it's an unofficial build. It's "built from source by merging Evervolvs Legacy code and HD2 related files," meaning it's a bit of a Frankenstein ROM, pieced together from several sources. You can head over to the XDA Forums thread right now to scope things out and see if you want to give this HTC HD2 Android 5.0 Lollipop ROM a spin.
The HD2 dropped in November 2009 with a 4.3-inch display, a 1GHz QSD8250 Snapdragon CPU, and 448 MB of RAM. The fact that it can run anything these days is mind blowing. The device ran Windows Mobile 6.5 out of the box, with HTC's Sense UI on top of that. This was running Sense before HTC ever loaded it on Android device. To give you some perspective, the HD2 was announced and released at the same time as the original Motorola Droid. The specs are similar, but I wasn't able to find a Lollipop ROM for the OG Droid. There are other devices out there like the Nexus One and Nexus S that are still alive and kicking, but the HD2 is the reigning king. Hit the source link below to see check the progress on this Lollipop HD2 ROM.